The present invention relates generally to a transducing device that includes a heater. In particular, the present invention relates to a magnetic head having a wide head-to-media contact surface.
In a magnetic data storage and retrieval system, a magnetic head typically includes a writer portion for storing magnetically-encoded information on a magnetic media and a reader portion for retrieving the magnetically-encoded information from the magnetic media. To write data to the magnetic media, an electrical current is caused to flow through a conductive coil to induce a magnetic field in a write pole. By reversing the direction of the current through the coil, the polarity of the data written to the magnetic media is also reversed.
During operation of the magnetic data storage and retrieval system, the magnetic head is positioned in close proximity to the magnetic media. The distance between the magnetic head and the media is preferably small enough to allow for writing to and reading from the magnetic media with a large areal density, and great enough to prevent contact between the magnetic media and the magnetic head. Performance of the magnetic head depends primarily upon head-media spacing (HMS). High density recording preferably requires a small HMS and a low fly height. Prior to using each magnetic head, there are small variations in fly height that must be accounted for due to changing operating conditions and head-to-head variations.
Current magnetic head designs use a heater to heat the magnetic head and reduce the HMS by controlled thermal expansion of the magnetic head. The heater is typically placed close to, or even inside, the writer coil to maximize heating of the writer. For effective operation, the heater must provide a large enough heater stroke when the write pole is either close to the magnetic media or only slightly recessed from the point at the storage interface surface where the writer protrudes most. In addition, the fly clearance must be measured for each magnetic head by a controlled measurable non-destructive head-media contact so that the proper algorithm for operating the heater is used for each magnetic head.
The head-media contact is typically detected by a signal that changes sharply when the head mechanically contacts a lube layer of the magnetic media. For example, the signal could be ΔPES (position error signal). To use ΔPES, the surface area of the head-media contact must be large enough so that when the thermally protruded magnetic head hits the lube layer of the magnetic media, the magnetic head component protruding most at the storage interface surface does not penetrate past the lube layer and start burnishing on the hard media surface, destroying the protective magnetic head layer.
In addition to the shape of the thermal protrusion produced by the heater, the storage interface surface topology can also largely impact the ability to detect contact between the magnetic head and the lube layer. In particular, if the write pole is positioned far away from the other metallic components of the head at the storage interface surface and protrudes above the surrounding alumina at a distance either comparable to, or greater than, the thickness of the lube layer, then the write pole can penetrate through the lube layer and burnish before a large enough head-media contact between the magnetic head and the lube layer is generated to be detectable.